This invention relates to loading mechanisms, and more particularly to lift devices suitable for hoisting handicapped persons with or without wheelchairs into vehicles such as buses or other types of public conveyance. It also relates to lift devices suitable for helping such persons in negotiating steps at the entrance of, within, or without a building. Lift devices which in the past were designed for vehicular use were relatively bulky and cumbersome, taking up a great deal of space in the interior of such vehicles. It is clearly preferable to have the lift devices completely contained in the vehicles when such vehicles are in motion. The large size of previous lift mechanisms has often necessitated external location of at least a portion of such equipment. The vehicle cargo capacity has often been greatly reduced by the portion of the lift mechanism located inside the vehicle. The size and complexity of such lift mechanism often requires that a special opening be cut into the side of the vehicle, in addition to the normal entrances, in order to accommodate the lifts.
Attempts have been made to install such a lift within the door well of a public transit bus. To that effect, various ingenious ways were devised for moving the normal entrace steps away from the path of the lift platform. My original design disclosed in U.S. Pat. No. 4,027,807, teaches how the tread and riser elements of the entrance steps can be recombined to form the load-carrying surface of the lift platform. In some cases, however, these tread and riser elements are too narrow to provide a platform length sufficient to carry a wheelchair. Additional platform space has been provided by stretching the width of one of the step elements with extensions telescopically mounted within such an element; or with a ramp sliding forward from under the step structure or platform. This invention is the result of a search for a more efficient way to expend the width of the lift platform.